The invention relates to novel liquid crystal compounds, and more particularly to novel smectic and ferroelectric liquid crystal compounds having a fluoroalkyl group.
The ferroelectric liquid crystal compounds are characterized by the molecular structure comprising at least one assymetric carbon atom in the molecule, having a large dipole moment in the direction vertical to the molecular apsis line and showing a smectic phase in which the molecular apsis line is tilted to the phase normal by a some degree. Such are generally optically active compounds having an optically active radical at the side chain.
Recently it has been made clear that the molecular structure of the optically active radical as well as the interaction between the assymetrical carbon part and the dipole moment carrying part may considerably affect on the liquid crystallization e.g. by J.W. Gooddy, E. Chin et al., J. Am Chem. Soc.108 4729-4735 (1986), ibid. 108 4736-4742 (1986). It has been tried, thus, to derive a liquid crystal compound from an optically active compound.
The optically active compounds used until now for that purpose are for instance derivatives of lactic acid, butyric acid, amino acid and an optical active 2-alkanol such as 2-octanol and amyl alcohol.
Perfluoro compounds having an optically active perfluoroalkyl radical, substituted with a perfluoroalkyl, perfluoroalkoxy or perfluoroalxenyloxy group are chemically, thermally or optically stable so as to be useful compounds for that purpose. Despite of that these compounds have not yet been used for the assymetric carbon part of the liquid crystal compounds, possibly due to that synthesis thereof has been though to be difficult.